How to visually rotate uv/image editor's canvas?
The UV/Image Editor is not intended to be a full fledged 2d editor like Gimp, Krita, or Photoshop, but to be a tool toward small editing and basic texture set up that might then be opened up in a better 2d editor. HOWEVER, I am somewhat of a blender addict and fell in love with the paint tools as they have been added through the GSOC a few years ago, and with some help from some pretty good friends worked on an addon to use the 3d view as a 2d editor. Result ended up being the Artist Paint Panel, and then evolved into the EZDraw panel. Coupled with the Texture Paint Plus version on my github as well as the EZdraw popup, there is a lot I do with 2d painting in the 3d view now - I almost only go to the 2d editor window just for the isolation of a single texture image versus the multi layer effect in the 3d view. FOr now it only works with Blender Render, but we will adapt it to Cycles as it becomes possible.